The present invention relates to a fluid-controlled actuator, particularly for controlling a clutch on a mechanical assembly, e.g. the transmission, reduction gear, or reversing gear of a vehicle or machine in general.
Mechanical assembly clutches are frequently operated using three-position fluid-controlled (hydraulic or pneumatic) actuators.
Known actuators of the aforementioned type comprise two pistons sliding in sealed manner inside a cylinder in which they define substantially three isolated chambers. One of the pistons usually presents an active rod secured to the mechanical member being controlled, whereas the outer is designed to slide inside the cylinder, and to cooperate with the first substantially for the purpose of adjusting its limit stop position. The aforementioned three positions are therefore achieved by supplying said chambers either selectively or in conjunction with one another.
Known actuators of the aforementioned type present numerous drawbacks. Firstly, they are fairly complex and expensive to produce, by virtue of featuring two pistons, and due to the mechanical machining required for the pistons and cylinder. Secondly, they require the use of relatively complex fluidic components. And thirdly, due to lack of a precise relationship between the position of the controlled member and that of the two pistons on the actuator, any means for detecting the position of the controlled member are activatable solely by the member itself or the "active" rod integral with the same, whereas, for certain applications said means may be preferably activated by the other rod for reasons of size and assembly.